Transdermal drug delivery devices are designed to deliver a therapeutically effective amount of drug across the skin of a patient. Devices known to the art include reservoir type devices involving membranes that control the rate of drug release to the skin and devices involving a dispersion of the drug in a matrix such as a pressure sensitive adhesive. The skin, however, presents a substantial barrier to ingress of foreign substances into the body. It is therefore often desirable or necessary to incorporate certain materials that enhance the rate at which the drug passes through the skin. However, the type of device, the transdermal flux rate that is suitable, and the suitable formulation components are dependent upon the particular drug to be delivered.
Testosterone is the main androgenic hormone formed in the testes. Testosterone therapy is currently indicated for the treatment of male hypogonadism. It is also under investigation for the treatment of wasting conditions associated with AIDS and cancer, testosterone replacement in men over the age of 60, osteoporosis, combination hormone replacement therapy for women and male fertility control.
In recent years there has been interest in developing a useful method of delivering testosterone transdermally to both men and women. Ebert et al., U.S. Pat. No. 5,152,997, describes a device for the transdermal delivery of testosterone that contains testosterone in a matrix that additionally includes a penetration enhancer. In U.S. Pat. No. 5,460,820 Ebert et al. describe a device for providing testosterone replacement therapy to women that delivers 50 to 500 .mu.g/day testosterone to the woman. The '820 devices may also include an estrogenic compound, thereby providing combination hormone replacement therapy. Pike et al., U.S. Pat. No. 5,340,586 also describes compositions that can be used to provide estrogens and androgens to women in amounts effective to prevent the symptoms of loss of ovarian function.